or M.M.S.
A severe mental syndrome characterized by excessive grinding of the teeth and chewing of the jaw. Named after the famous actress Mary McDonnell who developed this rare and unheard of syndrome during the shooting of the film "Donnie Darko" (her chewing is seen in the family dinner scene) Patients are usually extremely angry and unstoppable when having MMS.
There is no cure for MMS and comes and goes in various frantic episodes. Patients must usually be strapped down to prevent assault on others.

A typical episode characterizes the slight jaw movement on a patient. The patient loses his patience and begins eating extremely fast and angrily. MMS patients get extremely thirsty due to excessive chewing of the gums, so they typically angrily and quickly drink large amounts of water in short periods of time. The patient then gets impatient with everyone around him, usually succumbing to fits of rage and chewing on other people. The MMS patient is fully aware of the oncoming and happenings of MMS, but they simply cannot control it. They typically leave or go for a run due to embarrassment. All of these characteristics of Mary McDonnell Syndrome. The whereabouts of Mary are still unknown today.